This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The Sulfs are a family of extracellular endosulfatases that modify heparan sulfate (HS) chains at cell surfaces and in extracellular matrices. They release sulfate groups at the 6-O-position of a subset of glucosamine residues in HS chains. The activity of Sulf enzymes serves to potentiate activities of growth factors including GDNF, BMP, Shh, and Wnt and to reduce activities of FGF2, HP-EGF, HGF, and TGF-[unreadable]. As a result of these activities and depending on the context, Sulfs have been observed to serve as oncogenic effectors and as tumor suppressors. Sulf activities appear to induce changes in expression of biosynthetic enzymes, resulting in changes in expressed HS structure that do not necessary reflect the direct Sulf enzymatic activity. As a result, the influences of Sulf activity on cellular phenotype are complex. The goals of this work are to (1) define the HS structural phenotype in mouse embryonic fibroblast cells as a function of Sulf enzyme knockout at both the HS disaccharide and oligosaccharide levels. These results will be compared against those obtained using recombinant Sulf enzymes on purified HS.